Interface based Design Donald Chai EE249 Interface based Design Outline Orthogonalization of concerns Formalisms Interface based Design Example Cheetah Simulator Future Inroads Orthogonalization of Concerns Behavior Communication or computation coordination or interfaces These two are or should be independent Interface based Design Done all the time OSI stack Memory mapped I O Virtual memory Required Tools A good formalism with which to perform Abstraction and hierarchy Decomposition and composition These concepts exist for both computation and communication Formalism Models of Computation All models of computation specify a set of actors and a communication mechanism FSMs synchronous composition CFSMs event broadcast Dataflow KPN lossless queues CSP rendezvous Some models conflate communication and computation Refinement Abstraction 1 Simple channel through which tokens are passed REQ ACK protocol 1 2 3 Master requests slave acknowledges Repartition De composition Largely ignored in this paper Consider at least three communicating processes Design Example What Software thread sending packets through a hardware transmitter Asynchronous Transfer Mode ATM How Communication through bus PCI EISA or PI Single byte transmission or burst mode Cheetah Simulator Event driven Built with communication platforms Cheetah Simulator II At most abstract level channel has a simple delay With more detail expands in both space and time Simulation speed varies from 7x to 175x RTL Future Inroads Better Can mix and match communication and behaviors Better modeling and design exploration synthesis Allows design reuse Improves don t care extraction Composeability Future Inroads II Verification Abstraction and Decomposition are necessary Can be used between steps in communication platform Formal specification allows test generation
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